Electrolytic method and apparatus



K. E. STUART ELECTROLYTIC METHOD AND APPARATUS May- 24 Filed Mafch s; 1925 Qtain absolute separation between the caustic 30 is the concentration salt in the anode com-- lie tented May 24, 19 27. I

. UNITED STATES- Teutonic-E.

' KENNETH n STUART, or memrnts. NEW YORK, assreuon 'ro nooxnn nLncrao- CHEMICAL COEPANY, OF NEW YORK,

N. YL, CORPORATIONOF NEW YORK.

nnncrnonxrrc METHOD AND arram'rusr 1 Application filed March 5, 1925. a Serial No. 18,285.

' The invention'relates a method of and apparatus for the electrolytic decompositionof soluble salts, and is particularly useful in connection with the decomposition-of the ale.--

6 kalichloridessuch as'those of sodium and potassium. In the 'followin description reference will be made 'to the decomposition of sodium chloride, but the invention is not limited to the decomposition of a particular 10' salt. f 1

Electrolytic operations of this nature are frequently carried out in cells of relatively great length as compared to their width or height, the electrodes comprising vertically 1 disposed elements which. are separated from each other by porous diaphragms extending longitudinallyof the cell. Y

It is well known that in cells of this type no diaphragm, however-perfect, can mainsoda and-the-chlorine, since the diaphragm must be .porousin order to function at all, and this-porosity will always permit of a certain back migration of sodium ions intothe anode compartment, where they. combine with chlorine to form sodium chlorate. This represents an impurityfand a loss of efliciency. One of the mostimportant factors affecting the back mi ation of sodium ions partment. For this reason, it is desirable to keep the brine in this com artment as near the saturation point as possible; But if only saturated brine be fed to the cell, the brine in the anode compartment will be found after several hours to be considerably below the saturation point, due probably to, the

fact-that the electrolytic action carries the salt throughthe-diaphragm faster. than the '40 water passes through byordinary percolation.- The dilution of the brine does not go v on indefinitely, but before the process becomes s'tabiliaedthe dilution may reach such a point that chlorates are'formed to an ex- 4 tent resulting in serious loss of efficiency.

If saturated brine is fed to the cell at one point only, as is now customary, the electrolyte will be near saturation only in the immediate vicinity of the infee d. At points remote from the infeed-the electrol te be much belowsaturation, and at suc places -.the formation of chlorates' will be ra id. 7 One way-of minimizing this efiect'is to. eed to the cell more salt than can becarried in More specifically ianobject is to provide a lution of the excess salt carried into the cell cell, taken on the line 1'1 of Fig. 2, and,"

- not material since the invention is applicable solution, the'excess being in finely divided form and carried in suspension, as illustrated ln'Patent No. 1,423,584,.grantcdlt0 me on July 25, 1922. .Whether undissolved salt is fed to the cell in suspension in the brine or not, the dilution within the cell will be mini- 0 'mized if circulation can be set up from the point of infeed toward the remote parts of the cell, and if excess salt, is fed in suspension, it is all the more desirable that there should be such circulation, otherwise such salt may settle undissolved to the bottom of the ca g Objects of this invention are to provide a method and apparatus for securin a circu- 'latlon of the electrolyte within" an longitudmally' of a cellin such manner'that a substantially. uniform concentration of the electrolyte is maintained throughout the cell.

method 'of and apparatus for securing a longitudinal circulation of the electrolyte by means of the gaseous roduct given off at the anode. A further dbject is to provide a method of and apparatus for securing a soin: suspension.

A typical construction in accordance with this invention isillustrated onfthe accom p'anying drawings in which Fig. 1 is 'a transverse section through the -86' Fig; 2 is a longitudinal central section -0 the line 2+2 of Fig. 1. I

In the drawings, the numeral 1 desig-' nates the' open-sided frame or body portion 90 of the cell, which frame or body portion formed of concrete or other non-conducting, chlorine-resistant material. Diaphragms. 2 and perforated cathode plates 3 are a plied. to-the sides of the frame'l, thecatho es being enclosed byside plates 4 which form the cathode compartments having outlets 5, 6- for caustic soda andhydrogen, respectively.v A. series of anodes, such as graphite blades7,

are arrangedadjacent each of and parallel to a the catho es 3. The blades 7 are attached to graphite posts 8, and through the latter and ribbons 9, are connected to the busbars 10. I

Theexact construction of these parts-is to any cell of relatively great length .in

whicha series of anodes aymg active faces V directed transversely of the cell are dis? i posed in longitudinal alignment. In accordance with my invention, I provide a circulation of the electrolyte longitudinally of the cell by diverting the chlorine evolved fat the anodes along a submerged path extending longitudinally of the cell. As

shown in Fig. 2,1 may provide a false top 11 which extends across the cell below the level of the electrolyte and is spaced from the end walls of the frame 1. The lower face of the false top 11 is provided with channels 12 which slope upwardly from the ends of the top towards a restricted Venturishaped orifice 13, which is preferably at the middle point ofthe cell. .The feed pipe 14 for delivering brine to the cell 'is arranged above and with its opening at the upper end of the orifice 13. The feed-pipe 14 is supplied through a goose-neck 15 which due to the chlorine rising upthe face of the '35 transversecirculation, a longitudinal circuanodes, the return flow being downward between the anode blades. In addition to this lation is set up by thestream of chlorine which escapes through the orifice 13, carrying with it the brine which is entrained as in an air-lift pump. The brine which is liftedby the vigorous upward flow through the orifice enters the longitudinal passage.

lying between the false top 11 and the" top member-of the frame 1, in which passage the stream divides, flowing each way towards the ends of the cell from which points it returns to the main anode compartments, as indicated by the arrows'in Fig. 2. 4 Due to the location of the infeed pipe 14 beneath the surface and directly'over the orifice, the

excess salt in suspension in the infeed brine is immediately taken up by the upwardly rising streamof'u'nsaturated brine.

Both the longitudinal circulationa'nd' the rapid solution of the excess salt, when combined with the transverse circulation, result in a nearly equal distribution, to every anode, of the'fresh brine supplied through.

a single infeed. v

' It isto be understood that the'invention is not limited to the specific form and 'arqrangement of parts chosen for illustration, inasmuchas these are capable of being mo di-' yfied in numerous ways without de artmg f'romthe spirit of my inventio 01 ex- As the chlorine can enter the ample, in, comparatively short cells, the

chlorine stream could be deflected to a Venturi orifice located adjacent one end of the cell, and'with such an arrangement or with that illustrated, the anodes may be of special I design or arrangement to promote the transverse circulation of the brine. These and other modifications fall within the scope of my invention as set forth in the following claims.

I claim v 1. The method of maintaining a uniform concentration of the electrolyte in a cell hav-' ing longitudinally arranged electrodes which comprises diverting the gaseous product evolved at an electrode along a submerged path extending longitudinally of the cell. 2. The herein described method which comprises establishing 'a circulation of the electrolyte within and longitudinally of the cell, and introducing super-saturated brine.

into said circulating stream of electrolyte at i a point of low concentration.

3. A cell for the electrolytic decomposition of soluble salts, said cell being of relatively great length as compared to its width or height, and being of the type having longitudinally aligned electrodes with transversely directed active faces, characterized by the provision of means cooperating with the evolved 'gaseous stream to create a circulation of the electrolyte longitudinally of the cell. n 4. The combination with an electrolytic cell of relatively great lengthand having upright electrodes provided with transversely. directed active faces, of means diverting the gaseous decomposition product along a submelrged path extending longitudinally of the ce 1.

5. The invention as claimed in claim 3 wherein said means comprises a false submerged top havlng an lnclinedchannel in its lower face, said channel termmatmg at an orifice extending through said false top;

6. In an electrolytic cell, the combination with a relatively long and narrow frame, of a false top located below the normal level of. the electrolyte, said top having an inclined gas channel in its lowerface, an'orifice through said top at the higher end of saidchannel, and means providing a passage for the return flow. of electrolyte carried through said orifice by the gas stream.

7. In an electrolytic cell, means operative to establish a circulation of brine within the cell, and means for "delivering infeed brine in counter flow to said circulating brine and at a'point'of relatively low concentration. g

8. In an electrolytic cell,

the combination" with upright electrode members having active faces disposed transversely of the. cell,

of means operativeto establish a. circulati n of the electrolyte longitudinally of the cell,

1,eso,224

and means for introducing infeed brine into said circulating electrolyte stream at a point of relatively lowconcentration.

9. In an electrolytic cell, an open frame, a submerged top providing a passage between the top member of said frame andthe anode compartment, an inclined channel provided in the lower face of said top, an

orifice through said top at the upper end of said channel, an opening spaced .from

c said orifice and connecting said passage and anode compartment, and an infeed pipe having a submerged discharge .openmg positioned above said orifice.

10. In an electrolytic cell, an open frame, a false top within said frame and having ends spaced from the end walls thereof,

channelsinlthe lower face of saidtop and' merged discharge opening locate above said orifice.

In testimony whereof, I aflix, my signature. Y

KENNETH E. STUART. 

